The size effect of the unsaturated cross intersection fracture flow

Abstract

The problem of water inrush is more prominent in deep coal mining.Due to complexity of geometry for rock mass fractures, there are still many difficulties in studying the seepage characteristics, especially, the rule of fluid flow in the cross fracture are less reported.In this paper, the seepage of cross fracture, with nine different sizes, was studied by using two-dimensional numerical analysis software Fluent.The size effects of fractures were analyzed from four aspects:pressure field, velocity field, water distribution field and fluid flow characteristics.The results show that the velocity and pressure in the range of longitudinal fracture are much larger than those in transverse fracture.The tendency of velocity with time is consistent with that of pressure at the same point.There is a critical value of longitudinal fracture between 0.1 mm and 0.3 mm that the surface tension is equal to the sum of the weight of the water and atmospheric pressure imposed by gas;and there is another critical value of transverse fracture between 0.3 mm and 0.5 mm that the surface tension equals the applied force of gas.

Keywords

• cross intersection fractured rock
• fluid flow
• size effect
• numerical experiment